1
\$\begingroup\$

AFAIK, most boost converters incorporate a diode or some mechanism for ensuring that current flows from the battery to the output. For instance, TPS61030's datasheet says that

This device however uses a special circuit which takes the cathode of the backgate diode of the high-side PMOS and disconnects it from the source when the regulator is not enabled (EN = low).

MPC6140's datasheet says that

With the EN pin pulled low, the output of the MCP1640B is isolated or disconnected from the input by turning off the integrated P-Channel switch and removing the switch bulk diode connection. This removes the DC path that is typical in boost con- verters, which allows the output to be disconnected from the input.

Does that mean if current tries to flow from output, these chips (at least these two?) won't be damaged at all? That is, for instance, there are two possible power sources connected in parallel, boosted to 5V. If only one is hooked up, would the current flowing into the other booster in reverse fry it?

What if both could be hooked up?

\$\endgroup\$
  • \$\begingroup\$ "P-channel switch" is a semiconductor device which can be damaged very likely by applying an excess voltage. Use flyback diode. \$\endgroup\$ – Eugene Sh. Aug 28 '15 at 14:36
  • \$\begingroup\$ If the other source is also boosted to 5V, could it still damage the MOSFET? Isn't it designed to handle 5V already? \$\endgroup\$ – John M. Aug 28 '15 at 14:41
  • \$\begingroup\$ You're OK unless you exceed the switch breakdown voltage. If you just have the rated output voltage on the output you should get no reverse current. You should check to be sure the part can start into a pre-biased (non-zero) output if you need to do that. \$\endgroup\$ – John D Aug 28 '15 at 14:48
  • \$\begingroup\$ @JohnD But could reverse current flow into the components in front of the shutdown logic? That is, does it heavily depend on where it sits on the current path? Based on the TPS61030 block diagram, VOUT is directly connected to the regulator without any MOSFET in between. Could reverse current fry the regulator in this setup? \$\endgroup\$ – John M. Aug 28 '15 at 14:58

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Browse other questions tagged or ask your own question.